Down's Syndrome, Society, and Abortion

Rym

There is an interesting article on the BBC indicating that, despite a massive increase in Down's Syndrome pregnancies, there has been an actual decrease in Down's Syndrome cases due to an over 90% abortion rate on tested positive fetuses.

The cause of the increase in affected pregnancies seems to be due almost exclusively to the growing prevalence of older women having children.

The ArticleThe risk of having a baby with Down's syndrome is one in 940 for a woman aged 30. But by age 40, the risk rises to one in 85.

What's interesting here is that accurate testing has led to the reduction in total cases, indicating that by and large people are more than willing to engage in pre-birth eugenics when it can prevent a crippling disease. Sadly, while this will prevent real-world cases effectively, it's unlikely that it will lower the long-term genetic prevalence of the disorder (there is no selection pressure against older people having children as a result of this, and Down's Syndrome sufferers can rarely procreate themselves). However, as prenatal testing becomes more practical, available, and accurate for a wider variety of crippling disorders, I foresee a coming sharp reduction in general, as people are clearly willing to go down this road.

At the same time, could this possibly, in the long run, cause a strange side effect? By and large, I would posit that as testing gets better, the majority of the parents choosing to either not be tested or to birth and raise severely disabled children will be religious or otherwise anti-abortion families. There are already socioeconomic divides between religious conservatives and the rest of society. Will this be one more such statistic?

lackofcheese

How accurate is the test for Down's syndrome?

TheWhaleShark

it's unlikely that it will lower the long-term genetic prevalence of the disorder

Down's Syndrome results from a failure to properly separate chromosomes that occurs during meiosis, IIRC. One of the gametic cells receives an extra 21st chromosome (or part of one) as a result of improper partitioning. I'm pretty sure there is a baseline random chance of this error occurring, so no matter, I'm fairly certain that the rate of occurrence will reach some plateau.

As for strange side effects, I doubt it. Down's Syndrome is a detrimental mutation, and aborting based on its presence will only reduce the frequency of the occurrence. Unless there was some significant association between Down's and some beneficial mutation (and I don't believe there is), you won't really hurt anything by removing such occurrences of a random mutation.

I strongly doubt this will significantly impact the finances of families that choose to keep a Down's child. In fact, I predict the emergence of a subculture (much like the Quiverfull movement), that will turn having a Down's child into a badge of honor. Much like the Duggars now, I see a community that would provide financial support to those who choose to proceed in that manner. It will eventually lead to a pronounced schism, though, as Down's Syndrome would become associated with (most likely) a largely religious movement, which I find to be strangely fitting. :P

So, I see more of a social ramification than anything else. There will emerge a culture that reveres the raising of Down's children.

Apreche

Down's Syndrome is a detrimental mutation, and aborting based on its presence will only reduce the frequency of the occurrence.

On question on this. Do people with Down's Syndrome reproduce? I can't imagine it happens that often. Therefore, will aborting fetuses with down's syndrome reduce the frequency that much more than it is already being reduced? If my guess is correct, and that people with the syndrome rarely reproduce, and the statistics show that the occurrence of fetuses with it are increasing, that means that it is something environmental rather than something hereditary which causes it.

Kate Monster

Is a child any more likely to have Down's Syndrome if one or both of their parents have Down's Syndrome?

lackofcheese

On question on this. Do people with Down's Syndrome reproduce?

I read that there is a 15-30% chance of fertility in women, but pretty much zero in men.

If my guess is correct, and that people with the syndrome rarely reproduce, and the statistics show that the occurrence of fetuses with it are increasing, that means that it is something environmental rather than something hereditary which causes it.

Yes - the "environmental" factor of old age.

Rym

Do people with Down's Syndrome reproduce?

No, they don't. Males are almost entirely incapable of fertilization, and females are unlikely to become pregnant.

Therefore, will aborting fetuses with down's syndrome reduce the frequency that much more than it is already being reduced?

If the abortion rate for tested positive babies is over 90%, then more widespread testing could theoretically eliminate the disorder from society on a practical scale, relegating it to the untested/non-aborted minority.

lackofcheese

I checked, and it seems the false positive rate is 1% or so. This means that if the test says your child has Down's syndrome, the probability of your child having Down's syndrome is 11% or so, all other things being equal. This probability would be around 9.5% for a woman aged 30, but around 54% for a woman aged 40. At what level of risk do you abort?

Cremlian

I think that trend you are looking for Rym is off set by the fact that religious people tend to have children at a younger age (and more of them) and therefore have less of a risk of Down's syndrome and will be more effected by the fact that if you have 8 kids you are generally going to be poorer and able to provide less then if you had 2 or 3. (unless the government intervened but generally these are the people who don't like that so much)

TheWhaleShark

Is a child any more likely to have Down's Syndrome if one or both of their parents have Down's Syndrome?

Probably. It's a chromosomal defect, so any gametes produced would be very likely to contain an additional 21st chromosome.

However, the vast majority of Down's persons do not (or cannot) reproduce.

Kate Monster

Is a child any more likely to have Down's Syndrome if one or both of their parents have Down's Syndrome?

Probably. It's a chromosomal defect, so any gametes produced would be very likely to contain an additional 21st chromosome.

I looked it up. Apparently, half of any children of a parent with DS will be born with DS as well.

Cremlian

Secular SaboteursI thought this might actually apply to where this thread is going.

Kate Monster

Secular SaboteursI thought this might actually apply to where this thread is going.

There is so much wrong with that article that I do not know where to begin.

lackofcheese

I'll repeat this - at what level of risk of Down's Syndrome do you abort?

GreatTeacherMacRoss

Secular SaboteursI thought this might actually apply to where this thread is going.

The only redeeming quality are the comments in which a majority of posters set the record straight. Donohue should be beaten with his own book.

Rym

I'll repeat this - at what level of risk of Down's Syndrome do you abort?

I would personally consider any risk greater than 50% to be unacceptable, but that's just me.

Rym

I think that trend you are looking for Rym is off set by the fact that religious people tend to have children at a younger age

Ahh, didn't think of that. In general, I'd wager more responsible people wait longer these days simply due to economic conditions.

lackofcheese

I'll repeat this - at what level of risk of Down's Syndrome do you abort?

I would personally consider any risk greater than 50% to be unacceptable, but that's just me.

Why 50%?
In any case, the risk of having Down's Syndrome given a positive test result will be above 50% past age 39 or so, in the absence of other factors.

Kate Monster

I'll repeat this - at what level of risk of Down's Syndrome do you abort?

That is entirely up to the parents. For me it would be determined by far more than percentage of likelihood. Other circumstances (how late into the pregnancy I was, the kind of resources I have available to aid in the rearing of a child with special needs, if I already had a child, etc.) factor into this decision beyond sheer statistics.

Rym

In any case, the risk of having Down's Syndrome given a positive test result will be above 50% past age 39 or so, in the absence of other factors.

That's why we have the test, which substantially reduces the margin of error. If the test is positive, it is extremely likely that the child does indeed have Down's Syndrome.

I use 50% as an absolute upper bound of acceptable risk. My practical threshold is probably much, much lower.

lackofcheese

That's why we have the test, which substantially reduces the margin of error. If the test is positive, it is extremely likely that the child does indeed have Down's Syndrome.

No. I said

In any case, the risk of having Down's Syndrome given a positive test result will be above 50% past age 39 or so, in the absence of other factors.

Bayes' theorem, people! If you're 39, to be 99% certain that your child has Down's Syndrome, given a positive test result, the test would have to be 99.99% accurate. If you're 30, it has to be 99.999% accurate. The numbers I see on the internet suggest this is plainly not the case.

If you want me to explain what Bayes' theorem is about, I can do so. Alternatively, there are TED videos on the subject.

Unless the test is ridiculously accurate, the 90% abortion rate seems quite disproportionate.

Dr. Timo

I checked, and it seems the false positive rate is 1% or so. This means that if the test says your child has Down's syndrome, the probability of your child having Down's syndrome is 11% or so, all other things being equal. This probability would be around 9.5% for a woman aged 30, but around 54% for a woman aged 40. At what level of risk do you abort?

Nice application of Bayesian priors there but you still fucked up. First of all the false positive rate is higher than 1% but this is for non-invasive testing.

After a positive screen test there are follow up tests (Amniocentesis, Chorionic Villus Sampling) which are extremely accurate and have practically non-existent false positive rates. They are not used as first tests since they have associated risks of miscarriage.

So, not to knock your neat ethical question, but your "risk" of aborting a healthy fetus is much, much lower than you make out.

lackofcheese

Thanks Timo. I couldn't find proper data on the overall accuracy with which Down's Syndrome can be detected, and I didn't know the deal with non-invasive vs invasive tests.

However, let's use Timo's data for to bring up some new questions (assuming 95% detection rate & 5% false positive rate, from Wikipedia, and Down's Syndrome rates by maternal age from here):
Age - Probability of Down's Syndrome given positive/negative non-invasive test result:
20-24 - 1.3% / 0.004%
33 - 4.3% / 0.01%
40 - 20.2% / 0.07%
45+ - 48.7% / 0.3%
Invasive tests have a 0.5% or 1% chance of miscarriage (from the previously-linked Wikipedia page). When is it justified to do an invasive test?

One approach is to equate Down's syndrome to death, and then to set about minimising the risk of unwanted death (as opposed to abortion, which is wanted death). In this case, the invasive test should be taken whenever the non-invasive test is positive, but never when the non-invasive. However, is this truly a reasonable standard?
At age 20-24, given a positive non-invasive test result, your child has almost as much chance of dying to CVS as having Down's Syndrome. Is it still fine to do a invasive test?

Rym

However, is this truly a reasonable standard?

For parents who are unable or unwilling to raise a severely disabled child? It's a perfectly reasonable standard in that case.

lackofcheese

Is it always reasonable to do an invasive test, even if the non-invasive test gives a negative result?

Rym

Is it always reasonable to do an invasive test, even if the non-invasive test gives a negative result?

That depends entirely on the situation.

lackofcheese

Is it always reasonable to do an invasive test, even if the non-invasive test gives a negative result?

That depends entirely on the situation.

I agree that legally, the option of invasive testing should always be available, in the same way that the option of abortion should always be available, but there needs to be some morally sound basis for deciding when and when or when not to do an invasive test. Let's define it more clearly.

Apreche

Here's a question.

Let's say you get tested, and there's an extremely good chance your kid will have down's syndrome, or some equivalently bad thing. Now let's say you decide not to abort. Ok, that's fine. But let's say that after you have the kid you try to give it up for adoption or something. Basically, society is now burdened with this person, and it could have been avoided.

Should we use laws to make sure this kind of thing does not happen? Should we make the testing mandatory? Should we prevent people from putting children with down's syndrome up for adoption if they tested positive and chose to have the baby anyway?

Starfox

But let's say that after you have the kid you try to give it up for adoption or something. Basically, society is now burdened with this person, and it could have been avoided.

Adoption is voluntary. It would only place a burden on those who willingly accept it.

Rym

Adoption is voluntary. It would only place a burden on those who willingly accept it.

Unadopted children are wards of the state, and must be cared for as such with taxpayer dollars.

Kate Monster

I agree that legally, the option of invasive testing shouldalwaysbe available, in the same way that the option of abortion shouldalwaysbe available, but there needs to be some morally sound basis for deciding when and when or when not to do an invasive test. Let's define it more clearly.

Why are you attempting to define something that is so completely subjective and has an almost endless list of other circumstances and factors that would contribute to the decision? This appears to be an attempt to bait the forum into an abortion argument.